1. Field of the Invention
Ophthalmic examining and photographic recording instruments with particular reference to means and method for achieving substantial pupil dilation for large field viewing of the fundus and increased obliquity of instrument alignment.
2. Discussion of the Prior Art
In viewing or photographing the ocular fundus the patient's normal pupil, acting as a field stop, limits the extent of the fundus available for any given angle of inspection.
In order to facilitate relatively easy, wider field inspection, mydriatic agents have been used where permitted by law. Their use is not casually employed since there are attendant risks. At the least, the patient is handicapped with blurred vision for relatively long periods and old posterior synechia may be torn and the crystalline lens absorbed.
Optical alignment of a fundus camera with invisible light in a darkened environment which promotes pupil dilation without mydriatics similarly handicaps the patient with prolonged blurred vision after photographic flashing, not to mention the attending traumatism of receiving a high intensity photoflash while accommodated to darkness.
It is, accordingly, an object of the present invention to achieve pupil dilation with minimal patient awareness or discomfort after photoflashing of the fundus whereby increased obliquity of viewing of the fundus may be accomplished for wide field inspection and displacement of corneal reflected image from the recording field.
Another object is to provide means and method for illuminating only a small area of the light-insensitive optic disc for effecting the aforesaid pupil dilation.
Other objects and advantages of the invention will become apparent from the following description.